The power switching devices under consideration are, for example, what are termed MCCB (Molded-Case Circuit Breaker) switching devices. In the case of a switching device of said kind the current requiring to be interrupted is interrupted before reaching its maximum value through pulling apart of the MCCB's switching contacts owing to adjacent conductors' electromagnetic repulsion, and the current's being interrupted thereby. The maximum current can be in the single- to three-digit kA range.
Alternatively or in addition, the switching contacts can be actuated by means of, for example, a preferably electromagnetically operable actuator. The actuator can be driven by, for example, an overcurrent-sensing unit.
The quenching packet(s) employed near the pairs of switching contacts or, as the case may be, double contact serve(s) to cool the hot arc plasma when the switching contacts open. Cooling the plasma causes the electric conductivity to be lowered such that the resistance in the arc will be increased, the reverse voltage increased, and the current interrupted.
What is problematic with the switching devices in current use is that the arcs occurring when the switching contacts open tend rather not to run into the cold metal sheets. It is known, for example, to employ what are termed blowout magnets to eliminate that problem. That, though, is not a satisfactory solution for all switching actions, or one that is too effort-intensive.